During the “Troubles”, attitudes to the IRA among Northern Ireland’s Catholics ran in an arc from outright support to unambiguous opposition. After 25 years or so, the organisation declared a ceasefire and abandoned its pursuit of a united Ireland through violence, but there was a price to pay: the inclusion of former terrorists in government, the release of criminals from prison, and the segregation of communities on a religious basis behind “peace lines”.

A poll last week found that eleven per cent of British Muslims believe that magazines which publish images of the Prophet Mohammed “deserve to be attacked”, that 27 per cent of respondents had “some sympathy” for the motives behind the Paris attacks, and that 20 per cent believe that western society is incompatible with Islam. This level of support and sympathy for terror or separatism or both is not very different from that which existed for the IRA in Ulster before it began its gradual journey to ending violence.

A similar settlement with ISIS and Al Qaeda or their fellow travellers as was reached in the province is neither practicable nor desirable – nor even possible. The IRA’s aim of a united Ireland can be pursued through peaceful politics. The Islamist objective of putting the entire country, or enclaves of its population, under pre-modern law cannot – at least, if we are to live under parliamentary government. There is no basis upon which, say, to release the 21/7 terrorists from prison, or to recall Abu Hamza and Abu Qatada and make them Ministers. We should not and cannot put up “peace lines” in Tower Hamlets.

In any event, Islamist terrorists are not en route to support for our political system. They hate Muslims who don’t support them, Jews, gay people, Christians, all the rest of us, the entire western project and norms of liberal democracy everywhere.

All this being so, our political leaders scratch and scrabble around looking for solutions commensurate to the challenge. David Cameron may have been unwise to widen his Munich speech about extremism into a more general critique of multiculturalism – which 71 per cent of Conservative voters support – but the policy thrust of his address was absolutely right, and he and the Conservatives have stuck to it in government. The disputes between Theresa May and Michael Gove were ones not of principle, but of practicality.

In short, the long, long dispute about whether one should seek to “shoot the crocodiles” or “drain the swamp” – to borrow Michael Gove’s terminology – which has divided the security services, the police, the civil service, the political parties and the infrastructure of the state since 7/7 has been resolved (at least for the time being). Ministers have quarantined groups who they believe are compromised by Islamist ideology, barred Zakir Naik and other hate preachers, sent Peter Clarke into Birmingham to investigate “Trojan Horse”, and begun to put an anti-extremism programme together.

The Charity Commission has been toughened up under the leadership of William Shawcross and more than 30,000 pieces of pro-terror material have been removed from the net. Theresa May has taken control of anti-extremism policy from Eric Pickles and CLG, which are more comfortable pursuing straightforward integration and extremism work. On terror itself, Abu Hamza and Abu Qatada have been removed, people arrested and prosecuted for offences related to terror in Syria, and passports seized.

There is always more to be done. Boris Johnson regrets the passing of Control Orders and their replacement by TPIMs (whose flaws Conservatives in the Home Office blame on the Liberal Democrats). May wants Banning Orders and Disruption Orders, so that groups which encourage and support terror, such as Al Muhajiroun and its successors, can be prosecuted. She and Downing Street are reported today to be at loggerheads with Vince Cable and the Liberal Democrats over further measures against hate preachers on campus.

This is not to say that the Home Office should get everything on its wish-list. There is a balance to be struck between measures that could perhaps provide greater security against terrorists, but would certainly compromise the civil liberties of everyone else. There is no guarantee that wide surveillance measures, of the kind ready to go in a Communications Date Bill, would not be abused by the state: RIPA offers a grim precedent. Cameron’s anti-encryption proposals were impracticable – at least, if we are to stay a liberal country. Most killers turn out to have been on the state’s radar in any event.

This is so of Mohammed Emwazi (“Jihadi John”), of Michael Adebolajo – who helped to murder Lee Rigby – and of Mohammed Siddique Khan, the ringleader of the 7/7 gang. The teenage girls who have left Britain for Syria were tiny droplets in the sea of support in which such men swim.

Their departure points to a central question. The state can arrest terrorists, confiscate passports, bar hate preachers from campus, prevent extremists from getting a grip in prisons, draw up new laws, even change its policy to target subversion…but all this will be like pulling up weeds and leaving polluted soil untreated if enough British Muslims remain sympathetic to the means and ends of terror. One of the terrorists’ main aims is to ensure that this becomes so – to bring Muslims into their camp and set them against that of their fellow citizens. How can government policy best ensure that this doesn’t happen? Must efforts to keep Muslims onside mean compromising, say, security policy or liberal values?

The answer of most non-Muslims and Muslims alike is that they do not, but for Ministers to take Britain’s Muslim population with them while simultaneously acting against terror and extremism is far from easy. What is happening here is only part of a civil war within Islam taking place worldwide, and its shock-waves reach far. Furthermore, it is not always clear where social conservatism ends and extremism begins – that’s to say, a hostility to Britain’s Parliamentary settlement and its norms.

One proposed solution to extremism is to make extreme secularism the norm – to remove state support from faith schools, for example. However, the schools that were compromised in Birmingham were not faith schools. Another is to treat Islam, rather than Islamism, as an exception and a problem in itself. But why should Muslims be unable to teach their children what their religion teaches about same sex marriage, for example, while traditional Christians and Jews are free to do so?

A nation-wide, grassroots movement against terror and extremism is needed. At a local level, there are many of them – lots of councils of Christians and Muslims, for example. Quilliam has blazed a trail by taking on extremism in all its forms. Ministers point tentatively towards such organisations as Inspire. Senior British Muslims, such as Shaykh Abdal Hakim Murad, balance criticism of British foreign policy, opposition to theological and political extremism within Islam, and a sense of the limits and flaws of materialism that is shared by bishops, rabbis and other religious leaders.

We are “wandering between two worlds, one dead/The other powerless to be born”. This struggle will last decades rather than years.